Devices of this kind (U.S. Pat. Nos. 4,326,447 and 4,353,446) each comprise two constantly driven rotors which are rotatable in opposite senses and driven by the motor through a power transmission which includes two oppositely rotating drive means. One of the two friction clutches cooperates in controlled manner with each of the rotors so that torques can be transmitted to the mass in both directions of rotation. With this kind of positioning and position stabilizing of the mass the motor which always is running at high speed must permanently drive the transmission connected upstream of the two rotors. The motor speed is kept constant at a high level so that a torque will always be available as required for a quick directional change of the mass at a speed level which is higher than the interference angle speed to be expected or the desired direction or aiming angle speed. Power transmission through the clutch causes severe slipping and this entails great power loss in the clutch to be made up by the motor.
The design and construction of the transmission requires great expenditure because of the fact that the motor always rotating at a high angular or rotational speed must drive the friction clutches by a common power transmission.
This applies also to another known device for positioning and position stabilizing an inert mass with which the motor drives a single rotor only. In this case a torque is transmitted to the mass by the rotor selectively in opposite senses by each of the two friction clutches, respectively, acting through a fork-like follower frame which is fixed to the mass (German Pat. No. 27 49 913). This requires an out-of-center arrangement of the friction clutches with respect to the rotor and, moreover, an out-of-center, space-requiring arrangement of the rotor with respect to the sluing axis of the mass.